Heretofore, a side-to-side leveling adjustment has been provided for a multiple spindle lawn mower wherein two separate rock shafts mounting laterally spaced ground wheels are disposed on parallel axes spaced from one another in the fore to aft direction. In the prior art construction, arms extending upwardly from adjacent inboard ends of the rock shafts are interconnected by an adjustable link thereby permitting the arm of one rock shaft to be adjusted angularly in relation to the arm of the other rock shaft.